Correlation Between Optical Fluorescence and Microwave Transmission During Single-cell Electroporation

Objective: Multimodal characterization of a mammalian cell by optical and microwave techniques simultaneously during electroporation. Methods: Using a coplanar waveguide with a Jurkat cell trapped in the middle of its center conductor, continuous waves at 100 kHz of different amplitudes were applied for 20 s while microwave transmission coefficients at 9 GHz were measured every 0.4 s. Results: The onset of electroporation was indicated by abrupt changes in both fluorescence intensity and transmission coefficient. Additionally, in measurements that lasted 300 s, the transmission coefficient was found to recover to the pre-poration level, while the fluorescence intensity remained different. Since the cells were confirmed viable through post-poration staining, the recovery of the transmission coefficient suggested reversible electroporation. Conclusion: These experimental results show that the transmission coefficient could serve as a label-free indicator of cell membrane permeability during and after electroporation. Furthermore, it can be used to expeditiously differentiate reversible electroporation from the irreversible one. Significance: This study should aid fundamental analysis of cell physiology, as well as molecular delivery in cell engineering and electrotherapy.